DocumentCode :
60061
Title :
Accurate Capacitor Voltage Ripple Estimation and Current Control Considerations for Grid-Connected Modular Multilevel Converters
Author :
Vasiladiotis, Michail ; Cherix, Nicolas ; Rufer, Alfred
Author_Institution :
Lab. of Ind. Electron., Ecole Polytech. Fed. de Lausanne, Lausanne, Switzerland
Volume :
29
Issue :
9
fYear :
2014
fDate :
Sept. 2014
Firstpage :
4568
Lastpage :
4579
Abstract :
In this paper, the analytical solution for the submodule voltage ripple equations of a modular multilevel converter (MMC) is derived, based on the knowledge of the external voltage/current magnitudes, and enhancing a concept previously presented in the literature. In order to achieve high accuracy, all passive elements of the converter, common-mode voltage injection as well as intentionally imposed circulating current harmonics are taken into consideration. The natural charge level mechanism of the capacitor voltages is also explained. As application examples, the three- as well as the two-phase grid-connected MMC cases are chosen. The control of line and circulating currents is also discussed and two respective independent feedback loops are formed. The concept of fictive-axis emulation is tailored for the two-phase MMC case, in order to achieve vector control of the line current and therefore straightforward desired injection of active and reactive power. Finally, the development of a reduced-scale laboratory prototype is presented and a full set of experimental results are provided, verifying the aforementioned concepts.
Keywords :
electric current control; power capacitors; power conversion harmonics; power grids; capacitor voltage ripple estimation; circulating current harmonics; common mode voltage injection; current control; grid connected modular multilevel converters; passive elements; reactive power injection; vector control; Capacitors; Current control; Equations; Estimation; Harmonic analysis; Mathematical model; Voltage control; Decoupled current control; fictive axis emulator (FAE); modular multilevel converter (MMC); prototype; voltage ripple estimation;
fLanguage :
English
Journal_Title :
Power Electronics, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-8993
Type :
jour
DOI :
10.1109/TPEL.2013.2286293
Filename :
6642060
Link To Document :
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